Year	years
1960	38.33
1961	38.333
1962	38.402
1963	38.473
1964	38.607
1965	38.812
1966	39.081
1967	39.427
1968	39.764
1969	40.193
1970	40.599
1971	40.94
1972	41.482
1973	41.91
1974	42.383
1975	42.774
1976	43.183
1977	43.619
1978	44.046
1979	44.349
1980	44.631
1981	44.983
1982	45.204
1983	45.383
1984	45.436
1985	44.664
1986	45.005
1987	44.528
1988	43.993
1989	43.451
1990	36.688
1991	42.795
1992	42.738
1993	42.166
1994	41.796
1995	43.917
1996	44.419
1997	47.847
1998	48.901
1999	49.953
2000	51.356
2001	52.752
2002	53.788
2003	53.042
2004	56.013
2005	56.912
2006	57.62
2007	58.285
2008	58.772
2009	59.194
2010	59.433
2011	59.62
2012	59.913
2013	59.943
2014	59.121
2015	59.148
2016	60.416
2017	60.553
2018	60.853
2019	61.104
2020	60.948
2021	60.747
2022	61.1